class_docstr: Shuffler is used to shuffle the data.
  
  data is stored in a flatten array with the shape is (num_node * node_size * step) and the
  shuffle is applied to the `node_size` dimension.
code: def __init__(self, num_node: int, node_size: int, seed: int):
      self.seed = seed
      self.num_node = num_node
      self.node_size = node_size
  
imports: from typing import List, Tuple, Dict
  import numpy
  import torch
label_desc: Use image node_id 1 to create a new Shuffler object  with example: obj = Shuffler(num_node, node_size, seed)